1. Field of the Invention
The invention relates to a global positioning system (GPS) antenna, and more particularly, to an open-loop GPS antenna.
2. Description of Related Art
As technology advances, current general public communications have been gradually replaced by wireless communications, such as cell phone, personal digital assistant (PDA) with wireless Internet access, global positioning system (GPS) and so forth, which are all within the scope of the wireless communications; however, the wireless communications normally require the use of an antenna for transmitting signal.
Frameworks of the antenna have different types, such as a dipole antenna, a bow-tie antenna and a horn antenna, that each has its own characteristics and performance, wherein the dipole antenna has an omnidirectional field, the bow-tie antenna has a wider operation band, and the horn antenna has a larger gain. However, each type of antenna also has its own relative drawbacks, for instance, the dipole antenna has a smaller gain and a narrower operational band, a field of the bow-tie antenna is much inconsistent when operating at each frequency, the horn antenna is not adapted to be used in a mobile communication and so forth. Therefore, a design of the antenna must be according to actual demands of the various wireless communications.
In terms of GPS antenna, current GPS is mostly using a patch type antenna that resonates at a frequency of 1575.42 MHz and is made of right-hand polarization ceramic dielectric materials as the antenna. The patch type antenna includes components such as a ceramic antenna and a low noise signal module (LNA). Currently, a dimension of the patch type antenna on the market is approximately between 1.2 cm×1.2 cm to 2.5 cm×2.5 cm. Current GPS electronic device becomes more and more strict in terms of slim and light weight requirements, and since a weight and a size of the patch type antenna are more difficult to be reduced, it occupies a certain volume of the wireless electronic device, and as in terms of the slim and light weight requirements, this is no doubt a limitation. Moreover, a production cost of the patch type antenna is also higher.